Decision Variables that are not in the objective function

José Joaquim de Andrade Neto

• June 19, 2019 12:12

Hello everyone,

I'm writing a model where I must use variables that are not defined in the objective function but only in the constraint set. For instance, my objective function is in the Figure below:

In the constraint set, I have a constraint, for example, that take usage of a variable x_{ij}^{c}, which are not in the objective function. This particular constraint is described below:

At first, I thought that I don't need to do anything besides use the x[i][j][c] = model.addVar(); method. But It seems that the x_{ij}^{c} does not make any difference in the model after all, and then I added the variable with a 0 coefficient to the objective function in order to investigate if any difference comes out, but I was not successful.

So how do I use variables that are defined only in the constraint set?

Best regards.

0

• 

  Daniel Espinoza

  • June 21, 2019 16:20

  Hi Jose,

  Defining variables without an objective coefficient is standard use. Maybe you are declaring your constraints wrong? Did you inspect the resulting model through the LP file?

  Daniel

  0

Please sign in to leave a comment.